Let’s face it: Pregnancy is a big deal.

It’s one of the most life-changing events in a woman’s life, and often one of the most stressful. As such, it’s easy to get worked up about how to “do pregnancy right.” And it’s particularly easy to focus on all the things that can go wrong.

As a registered dietitian specializing in maternal, infant and pediatric nutrition, one of the first questions I often get from pregnant clients is about avoidance: “What can’t I eat?”

As a general rule, I don’t like to offer too many prohibitions. I prefer to focus clients on the positive aspects of pregnancy nutrition – highlighting the importance of a diverse, healthful range of whole foods (accompanied, of course, by the occasional indulgent treat). But there are certain foods and food groups that are worth exercising caution over and/or avoiding all together.

Fish high in mercury

It’s important to remember that, in general, fish is good.

Fish and fish oils are considered the best sources of omega-3s, a family of polyunsaturated fatty acids that play a central role in both the healthy development of a baby and a healthy pregnancy itself. Studies have linked adequate omega-3 intake to neurological and visual development of the baby, reduced allergies and nervous system development. Omega-3s may also reduce risk of preterm labor, pre-eclampsia and post-natal depression.

However, some fish are contaminated with high levels of mercury, and mercury can affect brain development and the nervous system – some of the very same developmental processes that omega-3s are supposed to protect.

To maintain a safe fish intake and keep your omega-3s at a healthy level, eat fish considered low in mercury at least twice a week and/or supplement your diet with a good quality, purified fish oil. Fish to avoid, due to extremely high levels of contamination, include swordfish, king mackerel, shark, tilefish and bigeye or Ahi tuna.


Coffee isn’t technically a food. But for those of us who already have kids, it can definitely be a fuel.

However, caffeine can raise the heartbeat and blood pressure of the baby. A heavy intake of four or more cups a day has been linked to an increased risk of miscarriage. That doesn’t mean you have to go without entirely because you are pregnant, but moderation is definitely called for. About one small cup of coffee or tea (not a 20-ounce mug!) is fine.

Soft cheeses, lunch meats

Listeria is definitely a cause for concern in pregnancy. A bacteria that is found in both water and soil, listeria monocytogenes can be found in uncooked meats, vegetables and unpasteurized cheeses. Pregnant women are about 20 times more likely to become infected than the general population, and an infection can cause miscarriage, premature delivery or stillbirth.

Because listeria is killed by cooking and pasteurization, it’s recommended that pregnant women avoid raw milk, soft and unpasteurized cheeses like feta, brie or camembert. Pates, smoked seafood, sushi, as well as hot dogs and lunch meat – unless heated thoroughly – should also be avoided. All vegetables should be washed carefully before preparation, and it’s important to keep your fridge clean and wash hands regularly, especially during food preparation.


Because researchers have yet to determine what a “safe” level of alcohol intake might be during pregnancy (if a “safe” level exists at all), the official advice of most authorities remains to avoid alcohol all together during pregnancy, and certainly to avoid regular or heavy drinking.

Processed, junk foods

The old saying suggests that you are now “eating for two” – but this isn’t exactly true. Certainly your caloric needs are likely to increase significantly, but they will by no means double. On average, a pregnant woman needs about 300 more calories a day – the equivalent of half a sandwich or an extra bowl of cereal.

It can be tempting to turn to processed foods to fill the perceived calorie gap, whether it’s a fast-food hamburger, a candy bar or a bag of chips – and I’d never suggest we should deny ourselves an indulgence from time to time. But overindulging in processed foods is not going to do you or your baby any favors.

In general, you should look to fill your body with healthy, nutritious whole foods as much as possible, such as whole grains, vegetables, fruit and proteins, and to supplement those whole foods with a few key supplements like DHA fish oils and a general prenatal vitamin.